Compressibility of multiphase fluid in thermodynamic equilibrium at a given pressure p and temperature T is a simple sum of its single-phase components:
(1) | c_f(p, T) = \sum_{\alpha} s_\alpha \cdot c_\alpha(p,T) |
where
s_\alpha | \alpha-phase saturation, subjected to \sum_{\alpha} s_\alpha = 1 |
---|---|
c_\alpha(p, T) | \alpha-phase compressibility as function of pressure p and temperature T |
In most popular practical case of a 3-phase fluid model this will be:
(2) | c_f = s_w \, c_w + s_o \, c_o + s_g \, c_g |
where \{ w, \, o, \, g \} mean water phase, oil phase and gas phase.
See also
[Multi-phase pressure diffusion][Compressibility] [Single-phase fluid compressibility]